The invention concerns a tempering device for objects on the object carrier of a microtome in a cryostat, with an operating means supply connected to a cooling means or to a cooling and heating means disposed on the object carrier, and with a temperature control.
Tempering devices of this type permit cutting of frozen histological samples in a cryostat at different temperatures without having to change the temperature of the cryostat chamber. Different tissue types such as e.g. fat or brain can be optimally cut at different temperatures e.g. in the region between −30 and −35° or from −15°. Bringing the temperature of the entire cryostat chamber to the desired temperature would require a substantial amount of time. For this reason, the leaflet “Universal-Mikrotom-Kryostate Serie HM 500” offers an equipment variant “O” which is representative of the above-mentioned conventional tempering device. The cryostat chamber is thereby at an average temperature and the tempering device provides the desired object temperature.
In this tempering device, the operating means supply is directly guided away from the cooling means or the cooling and heating means disposed on the object carrier, laterally held by a bracket, and guided as a cable and tube bundle to the inner wall of the cryostat chamber. This arrangement is disadvantageous in that this operating means supply impedes work on the microtome, since it requires an excessive amount of space in that region where work has to be carried out on the microtome, such as sample and knife exchange. Moreover, this operating means supply exerts a force onto the object carrier due to its lateral arrangement, in view of its weight and the rigidity caused by the cold.
Such a one-sided force acting directly on the object carrier influences the cutting accuracy which must be in the p range for very fine sections.
A tempering device of the above-mentioned type with lateral path guidance of the operating means supply from the object carrier is also described in DE 196 40 044 A1. DE 19 62 263 U1 discloses a tempering device, from which the operating means supply is guided away from the object carrier in a manner which is not described in detail.
DE 195 28 180 C2 also discloses a power supply for a measuring amplifier used with means for detecting advance of the object head. This measuring element, however, is disposed downstream of the object head in an insulating body which is rigidly borne in a hollow cylinder serving as an object head carrier. The power supply exits the hollow cylinder and the lower side of the cylinder guidance in the form of a freely suspended cable harness, wherein the respective openings are dimensioned to prevent the cable from being clamped during the adjusting motions.
This document provides no suggestion for designing an operating means supply of a tempering device. A tempering device of this type must be located directly on the object carrier to be able to cool the object. If the operating means supply of a tempering device of the above-mentioned type were to be disposed on the rear side of the object head carrier, similar to the above-mentioned power supply, it would have to be guided through the object head carrier and the guiding carriage. The person skilled in the art is thereby confronted with the unsolved problem of how to replace and adjust the object head. Towards this end, the operating means supply should be guided through an object carrier receptacle in a separable manner and should not impair pivoting of the object carrier (designed as an articulated ball in the above-mentioned document) in order to orient it. Consequently, an arrangement of an operating means supply for a tempering device designed in accordance with the above-mentioned electrical supply is not possible or would require unacceptable technical effort. The operating means supply must rather be guided directly away from the tempering device, thereby producing the problems which were described in connection with the tempering device of the embodiment variant “O” of the above-mentioned cryostat.
It is therefore the underlying purpose of the invention to provide a tempering device of the above-mentioned type which does not impair work on the microtome and minimally impairs the cutting accuracy.